Ethylene-propylene copolymers with amorphous and semi-crystalline components

ABSTRACT

This invention relates to a polyolefin composition with (a) 80 to 90 wt % of an amorphous ethylene-propylene copolymer having either no crystallinity or crystallinity derived from ethylene, having about 30 wt % or more units derived from ethylene; (b) 5 to 15 wt % of a semi-crystalline ethylene-propylene copolymer having substantial crystallinity derived from ethylene and having 70 wt % or more units derived from ethylene; and (c) 1 to 5 wt % of a propylene-based elastomer having within the range from 5 to 25 wt % ethylene derived units and having a melting point temperature of less than 110° C. and a Mw/Mn within the range from 2.0 to 4.0.

PRIORITY CLAIM

This application claims the benefit of Provisional Application No.62/442,659, filed Jan. 5, 2017, the disclosure of which is incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates to an ethylene-propylene copolymer, wherethe composition of the ethylene-propylene copolymer has improved pelletstability.

BACKGROUND OF THE INVENTION

Polypropylene-based Thermoplastic Olefin Compositions (TPO) are blendsof polypropylene, an elastomer, optional propylene-based elastomers, andoptional non-polymeric components such as fillers and other compoundingingredients. Included in the category of TPO compositions are so calledimpact copolymers (“ICP”) compositions, typically non-cured. Typically,TPOs are multiphase polymer blends where a polypropylene forms acontinuous matrix phase and the elastomer component, generally derivedfrom an ethylene containing interpolymer, is the dispersed component.The polypropylene matrix imparts tensile strength and chemicalresistance to the TPO, while the ethylene polymer imparts stiffness andimpact resistance. Typically, ICPs and TPOs have a dispersed phase whichis not, or only modestly, cross-linked.

Traditionally, very low density ethylene-propylene copolymers andethylene-propylene-diene terpolymers have been used as the modifiercomponent in TPO compositions. The major market for TPOs is in themanufacture of automotive parts, especially bumper fascia. Otherapplications include automotive interior components, such as door skin,air bag cover, side pillars and the like. These parts are generally madeusing an injection molding process. Recently, other ethylene-alphaolefin copolymers have been used, especially very low densityethylene-butene, ethylene-hexene and ethylene-octene copolymers whichgenerally have a lower molecular weight expressed in Melt Index units.The density of these latter polymers is generally less than 0.900 g/cm³,indicative of little, if any residual crystallinity in the polymer. Suchlow crystallinity polymers tend to agglomerate into large, intractablepieces on storage. To increase efficiency and reduce costs, it isnecessary to decrease molding times and reduce wall thickness in themolds. To accomplish these goals, manufacturers have turned to high meltflow polypropylenes (Melt Flow Rate greater than 35 g/10 min). Thesehigh melt flow rate (MFR) resins are low in molecular weight andconsequently difficult to toughen, resulting in products that have lowimpact strength. Additionally, conventional traditional modifiercomponents do not have a balance of good low temperature toughness inblend with polypropylene while maintaining pellet stability.

There is a need, therefore, for TPO manufacturers to be able to broadenthe scope of polymers available to manufacture end use items with abetter balance between the performance of the hetero phase compositionin its end use, the processability during conversion of the moltencompositions into the end use article, a toughness at low temperaturewhile maintaining pellet stability, and the cost of providing thoseproperties.

References of interest include U.S. Pat. Nos. 6,245,856; 6,288,171;6,232,402; 5,959,030; US 2009/053959; WO 97/20888; US 2015/0025209, EP 0792 914, and WO 16/057124.

SUMMARY OF THE INVENTION

This invention is directed to a room temperature shape retentivepolyolefin blend composition comprising: (a) about 80 wt % to about 90wt % of an amorphous ethylene-propylene copolymer having either nocrystallinity or crystallinity derived from ethylene, having about 30 wt% or more units derived from ethylene; (b) about 5 wt % to about 15 wt %of a semi-crystalline ethylene-propylene copolymer having substantialcrystallinity derived from ethylene and having about 70 wt % or moreunits derived from ethylene; and (c) about 1 wt % to about 5 wt % of apropylene-based elastomer having within the range from 5 to 25 wt %ethylene derived units and having a melting point temperature of lessthan 110° C. and a Mw/Mn within the range from 2.0 to 4.0.

DETAILED DESCRIPTION

Disclosed is a blend composition containing an amorphousethylene-propylene copolymer (EP), semi-crystalline EP, and apropylene-based elastomer.

Various specific embodiments and versions of the present invention willnow be described, including preferred embodiments and definitions thatare adopted herein. While the following detailed description givesspecific preferred embodiments, those skilled in the art will appreciatethat these embodiments are exemplary only, and that the presentinvention can be practiced in other ways. Any reference to the“invention” may refer to one or more, but not necessarily all, of theembodiments defined by the claims. The use of headings is for purposesof convenience only and does not limit the scope of the presentinvention.

All numerical values within the detailed description and the claimsherein are modified by “about” or “approximately” the indicated value,and take into account experimental error and variations that would beexpected by a person having ordinary skill in the art.

Various terms as used herein are defined below. To the extent a termused in a claim is not defined below, it should be given the broadestdefinition persons in the pertinent art have given that term asreflected in at least one printed publication (e.g., a dictionary orarticle), issued patent or published application.

Polymer. Except as required by the particular context, the term“polymer” used herein is the product produced by particular continuouspolymerization in a particular polymerization zone or reactor.

Polymerization. As used herein, the term “polymerization” to be giventhe broadest meaning used by persons skilled in the art refers to theconversion of monomer into polymer. Polymerization zone refers to thezone in which polymerization takes place and is generally formed by aback mixed reactor for forming a substantially random polymer.

Polysplit. As used herein, the term “polysplit” shall mean thecalculated result of the weight of the first polymer (ethylene polymer)that is produced from the first polymerization zone divided by thecombined weight of the first polymer and the second polymer (propylenepolymer). The same definition applies equally to series and parallelreactor configurations. That is, the ethylene polymer is always regardedas the numerator.

Ethylene-Propylene Copolymer Containing Amorphous EP, Semi CrystallineEP

The combined ethylene-propylene copolymer is a blend of an amorphous EPand semi-crystalline EP. The blends described herein are formed ineither batch or continuous “multistage polymerization,” meaning that two(or more) different polymerizations (or polymerization stages) areconducted. More specifically, a multistage polymerization may involveeither two or more sequential polymerizations (also referred to hereinas a “series process”) two or more parallel polymerizations (alsoreferred to herein as a “parallel process”). Preferably, thepolymerization is conducted in a parallel process.

The polymers made in the respective reactors of the continuous, multiplereactor solution plant are blended when in solution without priorisolation from the solvent. The blends may be the result of seriesreactor operation, where the effluent of a first reactor enters a secondreactor and where the effluent of the second reactor can be submitted tofinishing steps involving devolatilization. The blend may also be theresult of parallel reactor operation where the effluents of bothreactors are combined and submitted to finishing steps. Either optionprovides an intimate admixture of the polymers in the devolatilizedblend. Either case permits a wide variety of polysplits to be preparedwhereby the proportion of the amounts of polymers produced in therespective reactors can be varied widely. The first polymer and secondpolymer making up the blend composition are discussed below. The processto make the first and second polymer is disclosed in U.S. PatentApplication Ser. No. 62/315,929, filed on Mar. 31, 2016, incorporatedherein by reference.

Combined Ethylene-Propylene Copolymer

The weight percent of ethylene-derived units of the amorphous EP ispreferably in the range of 35 wt % to 55 wt %; in some embodiments, inthe range of 40 wt % to 53 wt %; in other embodiments, in the range of45 wt % to 53 wt %; and in still yet other embodiments in the range ofabout 47 wt % to 52 wt %. The amorphous EP can have a weight percent ofethylene-derived units based on the weight of the combinedethylene-propylene copolymer (the amorphous EP and the semi-crystallineEP) ranging from a low of about 30 wt %, about 33 wt %, about 35 wt %,about 37 wt %, or about 40 wt % to a high of about 45 wt %, about 47 wt%, about 50 wt %, about 52 wt %, or about 54 wt %.

The weight percent of ethylene-derived units of the semi-crystalline EPis preferably in the range of 35 wt % to 85 wt %; in some embodiments,in the range of 55 wt % to 80 wt %; in other embodiments, in the rangeof 65 wt % to 80 wt %; in still other embodiments, in the range of 67 wt% to 80 wt %; and still yet other embodiments 67 wt % to 77 wt %; andstill yet other embodiments about 73 wt %. The semi-crystalline EP canhave a weight percent of ethylene-derived units based on the weight ofthe combined ethylene-propylene copolymer (the amorphous EP and thesemi-crystalline EP) ranging from low of about 60 wt %, about 63 wt %,about 65 wt %, about 67 wt %, or about 70 wt % to a high of about 80 wt%, about 83 wt %, about 85 wt %, or about 87 wt %.

In some embodiments, the ethylene weight percent of the amorphous EP maybe less than the ethylene weight percent of the semi-crystalline EP. Insome embodiments, the combined ethylene-propylene copolymer may becharacterized by the difference in the ethylene weight percent of theamorphous and the semi-crystalline EPs. In some embodiments, thedifference in the ethylene weight percent of the semi-crystalline EP andthe amorphous EP is greater than about 12; in other embodiments, greaterthan about 17; in still other embodiments, greater than about 21; instill yet other embodiments, greater than about 23. In some embodiments,the difference in ethylene weight percent is in the range of greaterthan about 17 and less than about 23; in other embodiments, thedifference is about 21. The difference between the weight percent ofethylene-derived units of the semi-crystalline EP and the amorphous EPcan range from a low of about 12, about 14, about 16, or about 18 to ahigh of about 20, about 22, about 23, or about 24.

The heat of fusion of the amorphous EP is in the range of 0 to less thanabout 30 J/g; in some embodiments, in the range of 0 to less than about15 J/g; in other embodiments, in the range of 0 to less than about 10J/g; in still other embodiments, in the range of 0 to less than about 5J/g; and in still yet other embodiments, the heat of fusion is about 2J/g. In one or more embodiments, the amorphous EP can have a heat offusion on ranging from a low of about 0 J/g, about 1 J/g, or about 2 J/gto a high of about 8 J/g, about 9 J/g, or about 10 J/g.

The heat of fusion of the semi-crystalline EP is in the range of 30 toless than about 60 J/g; in some embodiments, in the range of 35 to lessthan about 55 J/g; in other embodiments, in the range of 40 to less thanabout 50 J/g; and still yet other embodiments the heat of fusion isabout 45. In one or more embodiments, the semi-crystalline EP can have aheat of fusion ranging from a low of about 30 J/g, about 33 J/g, about35 J/g, or about 37 J/g to a high of about 47 J/g, about 50 J/g, about53 J/g, about 57 J/g, or about 60 J/g.

In some embodiments, the heat of fusion of the amorphous EP may be lessthan the heat of fusion of the semi-crystalline EP. In some embodiments,the difference in the heat of fusion of the semi-crystalline EP and theamorphous EP in J/g is greater than about 4; in other embodiments,greater than about 8; in still other embodiments, greater than about 12;in still yet other embodiments, greater than about 16.

The amorphous EP may be characterized by a weight-average molecularweight of less than or equal to 130,000, or less than 120,000, or lessthan 110,000, or less than 100,000, or less than 90,000, or less than80,000, or less than 70,000. Preferably, the weight average molecularweight is from 70,000 to 95,000. In one or more embodiments, theamorphous EP can have a weight-average molecular weight ranging from alow of about 60,000, about 65,000, about 70,000, or about 75,000 to ahigh of about 90,000, about 95,000, about 100,000, about 105,000, orabout 115,000.

The amorphous EP can have a concentration or content of ethylene-derivedunits ranging from about 50 mol % to about 70 mol % and a content ofcomonomer-derived units ranging from about 50 mol % to about 30 mol %.The amorphous EP can also have an MFR ranging from about 0.2 to about25. The amorphous EP can also have a molecular weight distribution(Mw/Mn) of from about 1.5 to about 3.

The amount of ethylene-derived units in the semi-crystalline EP, can begreater than about 70 mol %, greater than about 74 mol %, or greaterthan about 78 mol %. The semi-crystalline EP can also have an MFRranging from about 0.2 to about 25. The semi-crystalline EP can alsohave a molecular weight distribution (Mw/Mn) ranging from about 1.5 toabout 3.

Each discrete ethylene-propylene based copolymer can be polymerized in asingle, well stirred tank reactor in solution by a metallocene catalyst.The process to polymerize the amorphous EP and the semi-crystalline EPis described in U.S. Pat. No. 8,999,907, incorporated herein byreference.

The semi-crystalline EP may be characterized by a weight-averagemolecular weight of less than or equal to 130,000, or less than 120,000,or less than 110,000, or less than 100,000, or less than 90,000, or lessthan 80,000, or less than 70,000. Preferably, the weight averagemolecular weight is from 70,000 to 95,000. In one or more embodiments,the semi-crystalline EP can have a weight-average molecular weightranging from a low of about 60,000, about 65,000, about 70,000, or about75,000 to a high of about 90,000, about 95,000, about 100,000, about105,000, or about 115,000.

In some embodiments, ratio of the melt index of the amorphous EP to thatof the semi-crystalline EP is less than or equal to 3, less than orequal to 2, less than or equal to 1. The ratio of the melt index of theamorphous EP to the melt index of the semi-crystalline EP can be lessthan about 3.0, less than about 2.8, less than about 2.6, less thanabout 2.4, less than about 2.2, less than about 1.8, or less than about1.6.

In some embodiments, the absolute value of the difference in the meltindex of the amorphous EP and the melt index of the semi-crystalline EPis less than about 3.0; in other embodiments it is less than about 2.5;in still yet other embodiments, less than about 2.0; in still yet otherembodiments, less than about 1.5; in still yet other embodiments, lessthan about 1.1; and still yet other embodiments, less than about 1.0.

The amorphous or semi-crystalline EP can have a MWD of less than 3.0, orless than 2.4, or less than 2.2, or less than 2.0. Preferably, the MWDfor the amorphous and/or semi-crystalline EP is in the range of greaterthan or equal to 1.80 to less than or equal to 1.95.

In some embodiments, the comonomer insertion sequences of the amorphousand semi-crystalline EPs can be the same or different. The insertionsequences can provide linear polymer structure or substantially linearpolymer structure. The substantially linear structure of either theamorphous or semi-crystalline EP has less than 1 branch point pendantwith a carbon chain larger than 19 carbon atoms per 200 carbon atomsalong a backbone, less than 1 branch point pendant with a carbon chainlarger than 19 carbon atoms per 300 branch points, less than 1 branchpoint pendant with a carbon chain larger than 19 carbon atoms per 500carbon atoms, and preferably less than 1 branch point pendant with acarbon chain larger than 19 carbon atoms per 1000 carbon atomsnotwithstanding the presence of branch points due to incorporation ofthe comonomer.

Suitable comonomers include, but are not limited to, propylene (C₃) andother alpha-olefins, such as C₄ to C₂₀ alpha-olefins (also referred toherein as “α-olefins”), and preferably propylene and C₄ to C₁₂α-olefins. The α-olefin comonomer can be linear or branched, and two ormore comonomers can be used, if desired. Thus, reference herein to “analpha-olefin comonomer” includes one, two, or more alpha-olefincomonomers.

Examples of suitable comonomers include propylene, linear C₄ to C₁₂α-olefins, and α-olefins having one or more C₁ to C₃ alkyl branches.Specific examples include: propylene; 1-butene; 3-methyl-1-butene;3,3-dimethyl-1-butene; 1-pentene; 1-pentene with one or more methyl,ethyl or propyl substituents; 1-hexene with one or more methyl, ethyl orpropyl substituents; 1-heptene with one or more methyl, ethyl or propylsubstituents; 1-octene with one or more methyl, ethyl or propylsubstituents; 1-nonene with one or more methyl, ethyl or propylsubstituents; ethyl, methyl or dimethyl-substituted 1-decene, or1-dodecene. Preferred comonomers include: propylene, 1-butene,1-pentene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene,4-methyl-1-pentene, 3,3-dimethyl-1-butene, 1-heptene, 1-hexene with amethyl substituents on any of C₃ to C₅, 1-pentene with two methylsubstituents in any stoichiometrically acceptable combination on C₃ orC₄, 3-ethyl-1-pentene, 1-octene, 1-pentene with a methyl substituents onany of C₃ or C₄, 1-hexene with two methyl substituents in anystoichiometrically acceptable combination on C₃ to C₅, 1-pentene withthree methyl substituents in any stoichiometrically acceptablecombination on C₃ or C₄, 1-hexene with an ethyl substituents on C₃ orC₄, 1-pentene with an ethyl substituents on C₃ and a methyl substituentsin a stoichiometrically acceptable position on C₃ or C₄, 1-decene,1-nonene, 1-nonene with a methyl substituents on any of C₃ to C₉,1-octene with two methyl substituents in any stoichiometricallyacceptable combination on C₃ to C₇, 1-heptene with three methylsubstituents in any stoichiometrically acceptable combination on C₃ toC₆, 1-octene with an ethyl substituents on any of C₃ to C₇, 1-hexenewith two ethyl substituents in any stoichiometrically acceptablecombination on C₃ or C₄, and 1-dodecene.

Other suitable comonomers can include internal olefins. Preferredinternal olefins are cis 2-butene and trans 2-butene. Other internalolefins are contemplated. When an internal olefin is present, negligibleamounts, such as about 2 wt % or less of the total amount of theinternal olefin, can be present in the low ethylene-content copolymer,and most of the internal olefin, such as about 90 wt % or more of thetotal amount of the internal olefin, can be present in the highethylene-content copolymer.

Suitable comonomers can also include one or more polyenes. Suitablepolyenes can include non-conjugated dienes, preferably those that arestraight chain, hydrocarbon di-olefins or cycloalkenyl-substitutedalkenes, having about 6 to about 15 carbon atoms, for example: (a)straight chain acyclic dienes, such as 1,4-hexadiene and 1,6-octadiene;(b) branched chain acyclic dienes, such as 5-methyl-1,4-hexadiene;3,7-dimethyl-1,6; (c) single ring alicyclic dienes, such as1,4-cyclohexadiene; 1,5-cyclo-octadiene and 1,7-cyclododecadiene; (d)multi-ring alicyclic fused and bridged ring dienes, such astetrahydroindene, norbornadiene, methyl-tetrahydroindene,dicyclopentadiene (DCPD), bicyclo-(2.2.1)-hepta-2,5-diene, alkenyl,alkylidene, cycloalkenyl and cycloalkylidene norbornenes, such as5-methylene-2-norbornene (MNB), 5-propenyl-2-norbornene,5-isopropylidene-2-norbornene, 5-(4-cyclopentenyl)-2-norbornene,5-cyclohexylidene-2-norbornene, and 5-vinyl-2-norbornene (VNB); and (e)cycloalkenyl-substituted alkenes, such as vinyl cyclohexene, allylcyclohexene, vinyl cyclooctene, 4-vinyl cyclohexene, allyl cyclodecene;and vinyl cyclododecene. Of the non-conjugated dienes typically used,the preferred dienes are dicyclopentadiene (DCPD), 1,4-hexadiene,1,6-octadiene; 5-methyl-1,4-hexadiene; 3,7-dimethyl-1,6-octadiene;5-methylene-2-norbornene, 5-ethylidene-2-norbornene (ENB), andtetracyclo(Δ-11,12) 5,8 dodecene. It is preferred to use dienes which donot lead to the formation of long chain branches, and non- or lowlybranched polymer chains are preferred. Other polyenes that can be usedinclude cyclopentadiene and octatetraene; and the like. When a polyeneis present, the EPs can include up to 5 mol %, up to 4 mol %, up to 3mol %, up to 2 mol %, and up to 1 mol % polyene-derived units. In someembodiments, the amount of polyene, when present, can range from about0.5 mol % to about 4 mol %; about 1.0 mol % to about 3.8 mol %; or about1.5 mol % to about 2.5 mol %.

The amorphous and the semi-crystalline EPs can be combined such that theamorphous EP (typically the ethylene-based copolymer with a lower wt %ethylene) can be present in an amount of about 75 wt % to about 90 wt %,based on the combined ethylene-propylene copolymers. The amorphous andsemi-crystalline copolymers can also be combined in a predeterminedweight ratio such that the ethylene-based copolymer with greatercrystallinity (the semi-crystalline EP) can be present in an amount ofabout 10 wt % to about 25 wt %, based on the combined weight of the EPs.In one or more embodiments, the amorphous EP can be present in an amountless than about 65 wt %, less than about 60 wt %, less than about 55 wt%, less than about 50 wt %, or less than about 45 wt %, based on thecombined weight of the EPs.

Propylene Based Elastomer

As noted above, the blends herein preferably include at least onepropylene based elastomer, referred to herein as PBE.

The polymer blends used to form the TPOs described herein comprise oneor more PBEs. The PBE comprises propylene and from 5 to 25 wt % of oneor more comonomers selected from ethylene and/or C₄-C₁₂ α-olefins. Theα-olefin comonomer units may be derived from ethylene, butene, pentene,hexene, 4-methyl-1-pentene, octene, or decene. In preferred embodimentsthe α-olefin is ethylene. In some embodiments, the propylene-basedpolymer composition consists essentially of propylene and ethylene, orconsists only of propylene and ethylene. The embodiments described beloware discussed with reference to ethylene as the α-olefin comonomer, butthe embodiments are equally applicable to other copolymers with otherα-olefin comonomers. In this regard, the copolymers may simply bereferred to as propylene-based polymers with reference to ethylene asthe α-olefin.

The PBE may include at least 5 wt %, at least 6 wt %, at least 7 wt %,or at least 8 wt %, or at least 9 wt %, or at least 10 wt %, or at least12 wt % ethylene-derived units, where the percentage by weight is basedupon the total weight of the propylene-derived and ethylene-derivedunits. The PBE may include up to 30 wt %, or up to 25 wt %, or up to 22wt %, or up to 20 wt %, or up to 19 wt %, or up to 18 wt %, or up to 17wt % ethylene-derived units, where the percentage by weight is basedupon the total weight of the propylene-derived and ethylene-derivedunits. In some embodiments, the PBE may comprise from 5 to 25 wt %ethylene-derived units, or from 7 wt % to 20 wt % ethylene, or from 9 to18 wt % ethylene-derived units, where the percentage by weight is basedupon the total weight of the propylene-derived and ethylene-derivedunits.

The PBE may include at least 70 wt %, or at least 75 wt %, or at least80 wt %, or at least 81 wt % propylene-derived units, or at least 82 wt%, or at least 83 wt % propylene-derived units, where the percentage byweight is based upon the total weight of the propylene-derived andα-olefin derived units. The PBE may include up to 95 wt %, or up to 94wt %, or up to 93 wt %, or up to 92 wt %, or up to 90 wt %, or up to 88wt % propylene-derived units, where the percentage by weight is basedupon the total weight of the propylene-derived and α-olefin derivedunits.

The T_(m) of the PBE (as determined by DSC) may be less than 115° C., orless than 110° C., or less than 100° C., or less than 95° C., or lessthan 90° C. In some embodiments, the PBE may have two melting peaks asdetermined by DSC. In other embodiments, the PBE may have a singlemelting peak as determined by DSC.

The PBE may be characterized by its heat of fusion (Hf), as determinedby DSC. The PBE may have an Hf that is at least 0.5 J/g, or at least 1.0J/g, or at least 1.5 J/g, or at least 3.0 J/g, or at least 4.0 J/g, orat least 5.0 J/g, or at least 6.0 J/g, or at least 7.0 J/g. The PBE maybe characterized by an Hf of less than 75 J/g, or less than 70 J/g, orless than 60 J/g, or less than 50 J/g, or less than 45 J/g, or less than40 J/g, or less than 35 J/g, or less than 30 J/g, or less than 25 J/g.

Preferably, the propylene-based elastomer has within the range from 12to 20 wt % ethylene derived units and having a melting point temperature(T_(m)) of less than 110° C. Most preferably, the propylene-basedelastomer has a melting point temperature (T_(m)) within the range offrom 80, or 90° C. to 110° C. (first melt).

The PBE can have a triad tacticity of three propylene units (mmmtacticity), as measured by 13C NMR, of 75% or greater, 80% or greater,85% or greater, 90% or greater, 92% or greater, 95% or greater, or 97%or greater. In one or more embodiments, the triad tacticity may rangefrom 75 to 99%, or from 80 to 99%, or from 85 to 99%, or from 90 to 99%,or from 90 to 97%, or from 80 to 97%. The PBE may have a tacticity indexm/r ranging from a lower limit of 4 or 6 to an upper limit of 8 or 10 or12.

Certain propylene polymers have an isotacticity index greater than 0%,or within the range having an upper limit of 50%, or 25% and a lowerlimit of 3%, or 10%.

Certain propylene polymers can have a tacticity index (m/r) within therange having an upper limit of 800, or 1000, or 1200, and those polymersmay have a lower limit of 40, or 60.

The PBE may have a % crystallinity of from 0.5% to 40%, or from 1% to30%, or from 5% to 25%, determined according to DSC procedures.

The PBE may have a density of from 0.85 g/cm³ to 0.92 g/cm³, or from0.86 g/cm³ to 0.90 g/cm³, or from 0.86 g/cm³ to 0.89 g/cm³ at 22° C.

The PBE can have a melt index (MI), of less than or equal to 100 g/10min, or less than or equal to 50 g/10 min, or less than or equal to 25g/10 min, or less than or equal to 10 g/10 min, or less than or equal to9.0 g/10 min, or less than or equal to 8.0 g/10 min, or less than orequal to 7.0 g/10 min.

The PBE may have a melt flow rate (MFR), greater than 1 g/10 min, orgreater than 2 g/10 min, or greater than 5 g/10 min, or greater than 8g/10 min, or greater than 10 g/10 min. The PBE may have an MFR less than1,000 g/10 min, or less than 750 g/10 min, or less than 500 g/10 min, orless than 400 g/10 min, or less than 300 g/10 min, or less than 200 g/10min, or less than 100 g/10 min, or less than 75 g/10 min, or less than50 g/10 min. In some embodiments, the PBE may have an MFR from 1 to 100g/10 min, or from 2 to 75 g/10 min, or from 5 to 50 g/10 min.

In some embodiments, the PBE may be a reactor grade polymer, as definedabove. In other embodiments, the PBE may be a polymer that has beenvisbroken after exiting the reactor to increase the MFR.

The PBE may have a g′ index value of 0.95 or greater, or at least 0.97,or at least 0.99.

The PBE may have a weight average molecular weight (Mw) of from 50,000to 5,000,000 g/mol, or from 75,000 to 1,000,000 g/mol, or from 100,000to 500,000 g/mol, or from 125,000 to 300,000 g/mol. Most preferably, theweight average molecular weight (Mw) of the propylene-based elastomer isat least 150,000 g/mole; or within a range from 150,000, or 200,000g/mole to 300,000, or 400,000, or 500,000 g/mole.

The PBE may have a number average molecular weight (Mn) of from 2,500 to2,500,000 g/mol, or from 5,000 to 500,000 g/mol, or from 10,000 to250,000 g/mol, or from 25,000 to 200,000 g/mol. The PBE may have aZ-average molecular weight (Mz) of from 10,000 to 7,000,000 g/mol, orfrom 50,000 to 1,000,000 g/mol, or from 80,000 to 700,000 g/mol, or from100,000 to 500,000 g/mol. The molecular weight distribution (MWD, equalto Mw/Mn) of the PBE may be from 1 to 40, or from 1 to 15, or from 1.8to 5, or from 1.8 to 3.

Optionally, the propylene-based polymer compositions may also includeone or more dienes. In embodiments where the propylene-based polymercompositions comprises a diene, the diene may be present at from 0.05 wt% to 6 wt % diene-derived units, or from 0.1 wt % to 5.0 wt %diene-derived units, or from 0.25 wt % to 3.0 wt % diene-derived units,or from 0.5 wt % to 1.5 wt % diene-derived units, where the percentageby weight is based upon the total weight of the propylene-derived,alpha-olefin derived, and diene-derived units. Preferably, thepropylene-based polymer composition is substantially free of diene.“Substantially free” means less than 0.05 wt %.

In one or more embodiments, the PBE can optionally be grafted (i.e.,“functionalized”) using one or more grafting monomers. As used herein,the term “grafting” denotes covalent bonding of the grafting monomer toa polymer chain of the PBE. The grafting monomer can be or include atleast one ethylenically unsaturated carboxylic acid or acid derivative,such as an acid anhydride, ester, salt, amide, imide, acrylates or thelike. Illustrative monomers include but are not limited to acrylic acid,methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconicacid, mesaconic acid, maleic anhydride, 4-methylcyclohexene-1,2-dicarboxylic acid anhydride,bicyclo(2.2.2)octene-2,3-dicarboxylic acid anhydride,1,2,3,4,5,8,9,10-octahydronaphthalene-2,3-dicarboxylic acid anhydride,2-oxa-1,3-diketospiro(4.4)nonene, bicyclo(2.2.1)heptene-2,3-dicarboxylicacid anhydride, maleopimaric acid, tetrahydrophthalic anhydride,norbornene-2,3-dicarboxylic acid anhydride, nadic anhydride, methylnadic anhydride, himic anhydride, methyl himic anhydride, and5-methylbicyclo(2.2.1)heptene-2,3-dicarboxylic acid anhydride. Othersuitable grafting monomers include methyl acrylate and higher alkylacrylates, methyl methacrylate and higher alkyl methacrylates, acrylicacid, methacrylic acid, hydroxy-methyl methacrylate, hydroxyl-ethylmethacrylate and higher hydroxy-alkyl methacrylates and glycidylmethacrylate. Maleic anhydride is a preferred grafting monomer. In oneor more embodiments, the grafted PBE comprises from 0.5 to 10 wt %ethylenically unsaturated carboxylic acid or acid derivative, morepreferably from 0.5 to 6 wt %, more preferably from 0.5 to 3 wt %; inother embodiments from 1 to 6 wt %, more preferably from 1 to 3 wt %. Ina preferred embodiment, wherein the graft monomer is maleic anhydride,the maleic anhydride concentration in the grafted polymer is preferablyin the range of 1 to 6 wt %, preferably at least 0.5 wt %, and highlypreferably 1.5 wt %.

In some embodiments, the PBE is a reactor blend of a first polymercomponent and a second polymer component. Thus, the comonomer content ofthe PBE can be adjusted by adjusting the comonomer content of the firstpolymer component, adjusting the comonomer content of second polymercomponent, and/or adjusting the ratio of the first polymer component tothe second polymer component present in the propylene-based polymercomposition. In such embodiments, the first polymer component maycomprise propylene and ethylene and have an ethylene content of greaterthan 10 wt % ethylene, or greater than 12 wt % ethylene, or greater than13 wt % ethylene, or greater than 14 wt % ethylene, or greater than 15wt % ethylene, and an ethylene content that is less than 20 wt %ethylene, or less than 19 wt % ethylene, or less than 18 wt % ethylene,or less than 17 wt % ethylene, or less than 16 wt % ethylene, where thepercentage by weight is based upon the total weight of thepropylene-derived and ethylene derived units of the first polymercomponent. In such embodiments, the second polymer component maycomprise propylene and ethylene and have an ethylene content of greaterthan 2 wt % ethylene, or greater than 3 wt % ethylene, or greater than 4wt % ethylene, or greater than 5 wt % ethylene, or greater than 6 wt %ethylene, and an ethylene content that is less than 10 wt % ethylene, orless than 9.0 wt % ethylene, or less than 8 wt % ethylene, or less than7 wt % ethylene, or less than 6 wt % ethylene, or less than 5 wt %ethylene, where the percentage by weight is based upon the total weightof the propylene-derived and ethylene derived units of the secondpolymer component. In such embodiments, the PBE may comprise from 3 to25 wt % of the second polymer component, or from 5 to 20 wt % of thesecond polymer component, or from 7 to 18 wt % of the second polymercomponent, or from 10 to 15 wt % of the second polymer component, andfrom 75 to 97 wt % of the first polymer component, or from 80 to 95 wt %of the first polymer component, or from 82 to 93 wt % of the firstpolymer component, or from 85 to 90 wt % of the first polymer component,based on the weight of the PBE.

Polymerization of the PBE is conducted by reacting monomers in thepresence of a catalyst system described herein at a temperature of from0° C. to 200° C. for a time of from 1 second to 10 hours. Preferably,homogeneous conditions are used, such as a continuous solution processor a bulk polymerization process with excess monomer used as diluent.The continuous process may use some form of agitation to reduceconcentration differences in the reactor and maintain steady statepolymerization conditions. The heat of the polymerization reaction ispreferably removed by cooling of the polymerization feed and allowingthe polymerization to heat up to the polymerization, although internalcooling systems may be used.

Further description of exemplary methods suitable for preparation of thePBEs described herein may be found in U.S. Pat. Nos. 6,881,800;7,803,876; 8,013,069; and 8,026,323.

The triad tacticity and tacticity index of the PBE may be controlled bythe catalyst, which influences the stereoregularity of propyleneplacement, the polymerization temperature, according to whichstereoregularity can be reduced by increasing the temperature, and bythe type and amount of a comonomer, which tends to reduce the level oflonger propylene derived sequences.

Too much comonomer may reduce the crystallinity provided by thecrystallization of stereoregular propylene derived sequences to thepoint where the material lacks strength; too little and the material maybe too crystalline.

The catalyst systems used for producing the PBE may comprise ametallocene compound. In any embodiment, the metallocene compound may bea bridged bisindenyl metallocene having the general formula(In¹)Y(In²)MX₂, where In¹ and In² are identical substituted orunsubstituted indenyl groups bound to M and bridged by Y, Y is abridging group in which the number of atoms in the direct chainconnecting In¹ with In² is from 1 to 8 and the direct chain comprises C,Si, or Ge; M is a Group 3, 4, 5, or 6 transition metal; and X₂ areleaving groups. In¹ and In² may be substituted or unsubstituted. If In¹and In² are substituted by one or more substituents, the substituentsare selected from the group consisting of a halogen atom, C₁ to C₁₀alkyl, C₅ to C₁₅ aryl, C₆ to C₂₅ alkylaryl, and Si—, N— or P— containingalkyl or aryl. Each leaving group X may be an alkyl, preferably methyl,or a halide ion, preferably chloride or fluoride. Exemplary metallocenecompounds of this type include, but are not limited to,μ-dimethylsilylbis(indenyl) hafnium dimethyl andμ-dimethylsilylbis(indenyl) zirconium dimethyl.

Suitable PBEs for use in the present invention includes Vistamaxx™grades available from ExxonMobil Chemical, such as Vistamaxx™ 6102.

The propylene polymer preferably comprises >60 wt %, more preferably >75wt % propylene-derived units. In some embodiments, the propylene polymercomprises from 75-95 wt % of propylene-derived units, more preferablyfrom 80-90 wt % of propylene-derived units, the balance comprising oneor more .alpha.-olefins. Other suitable embodiments include propylenederived units in an amount (based on the weight of propylene andalpha-olefin) ranging from about 75-93 wt %, more preferably about75-92.5 wt %, more preferably about 75-92 wt %, more preferably 75-92.5wt %, more preferably 82.5-92.5 wt %, and more preferably about 82.5-92wt %. Corresponding .alpha.-olefin ranges include 5-25 wt %, morepreferably 7-25 wt %, more preferably 7.5-25 wt %, more preferably7.5-17.5 wt % and more preferably 8-17.5 wt % (based on the weight ofpropylene and alpha-olefin). A preferred alpha-olefin is ethylene. Thepropylene polymer preferably has a MFR<about 800, more preferably <about500, more preferably <about 200, more preferably <about 100, morepreferably <about 50. Particularly preferred embodiments include apropylene polymer with an MFR of from about 1-25, more preferably about1-20. The crystallinity of the propylene polymer should be derived fromisotactic polypropylene sequences. The isotacticity of the propylenepolymer can be illustrated by the presence of a preponderance of thepropylene residues in the polymer in mm triads. As noted elsewhereherein, the tacticity of the propylene polymer is preferably greaterthan the tacticity of either the reactor blend or the ethylene polymer,e.g., where the propylene polymer is isotactic and the ethylene polymeris atactic.

For the propylene polymer, at least 75% by weight of the polymer, or atleast 80% by weight, or at least 85% by weight, or at least 90% byweight, or at least 95% by weight, or at least 97% by weight, or atleast 99% by weight of the polymer is soluble in a single temperaturefraction, or in two adjacent temperature fractions, with the balance ofthe polymer in immediately preceding or succeeding temperaturefractions. These percentages are fractions, for instance in hexane,beginning at 23° C. and the subsequent fractions are in approximately 8°C. increments above 23° C. Meeting such a fractionation requirementmeans that a polymer has statistically insignificant intermoleculardifferences of tacticity of the polymerized propylene.

Composition

Additives may by present in the compositions described herein and arepreferably present, if at all, to an extent that does not negativelyinfluence the impact or modulus of the composition or components madefrom the composition. The “additives” include fillers (especiallysilica, glass fibers, talc, etc.) colorants, whitening agents,cavitation agents, antioxidants, anti-slip agents, antifogging agents,nucleating agents, and other additives common in TPO compositions usefulin automotive components. Other useful additives include stabilizers,mold release agents. Primary and secondary antioxidants include, forexample, hindered phenols, hindered amines, and phosphates. Nucleatingagents include, for example, sodium benzoate and talc. Dispersing agentssuch as AcroWax C can also be included. Slip agents include, forexample, oleamide and erucamide. Catalyst deactivators are also commonlyused, for example, calcium stearate, hydrotalcite, and calcium oxide.Preferably, the additive is talc in the amount of about 5 wt % to about30 wt %, preferably about 10 wt % to about 25 wt %, most preferablyabout 20 wt % based on the weight of the composition.

The inventive compositions are most often described as a combination ofits components and the properties of those components, but preferablythe composition has a total ethylene content within the range of 6, or10, or 12 to 16, or 18, or 20, or 24 wt %. The composition can be usedto form any number of articles, which typically includes melt blendingthe components described herein and forming them into articles eitherbefore or after allowing the melt to cool. The “cooled melt blend” isthus the reaction product of melt blending the components, taking intoaccount the possibility that there could be some transformation of oneor more of the components facilitated by the heating and/or mixingprocess.

Useful Articles.

Preferred compositions herein are particularly useful for automotiveapplications, preferably for making molded high impact automotive partssuch as car bumpers, e.g., bumper fascia. These compositions are blends,preferably physical blends, which have high impact and improvedductility.

Examples of automotive articles that can be made from one or more of thecompositions described above or elsewhere herein include exterior orinterior car components. More specific embodiments of such automotivearticles include bumper fascia, fender liners, wheel well covers, bodyside moldings, pillar trim, door trim panels, consoles, instrument panelend-caps, instrument panel trims, airbag covers, glove box bins, rearquarter panels, lift gate panels, seat back covers, airbag components,airbags, instrument panel covers, dash board skins, air dams andheadliner cartridges.

The various descriptive elements and numerical ranges disclosed hereinfor the inventive compositions can be combined with other descriptiveelements and numerical ranges to describe the invention(s); further, fora given element, any upper numerical limit can be combined with anylower numerical limit described herein, including the examples. Thefeatures of the invention are demonstrated in the following non-limitingexamples.

Polymer Analysis

The DSC procedures for determining T_(m) and Hf include the following.The polymer is pressed at a temperature of from 200° C. to 230° C. in aheated press, and the resulting polymer sheet is hung, under ambientconditions (20-23.5° C.), in the air to cool. 6 to 10 mg of the polymersheet is removed with a punch die. This 6 to 10 mg sample is annealed atroom temperature (22° C.) for 80 to 100 hours. At the end of thisperiod, the sample is placed in a DSC (Perkin Elmer Pyris One ThermalAnalysis System) and cooled at a rate of about 10° C./min to −30° C. to−50° C. and held for 10 minutes at −50° C. The sample is heated at 10°C./min to attain a final temperature of 200° C. The sample is kept at200° C. for 5 minutes. Then a second cool-heat cycle is performed, usingthe same conditions described above. Events from both cycles, “firstmelt” and “second melt”, respectively, are recorded. The thermal outputis recorded as the area under the melting peak of the sample, whichtypically occurs between 0° C. and 200° C. It is measured in Joules andis a measure of the Hf of the polymer. Reference to melting pointtemperature herein refers to that recorded during the first melt.

Crystallinity is expressed as a percentage and for the propylene-basedelastomers is determined by dividing the Hf in J/g by 88 J/g andmultiplying by 100%.

Triad tacticity is determined by the methods described in U.S. Pat. No.7,232,871.

Density is determined by ASTM D-792 test method.

Melt Index (MI) is measured per ASTM D-1238, 2.16 kg at 190° C.

Melt Flow Rate (MFR) is measured per ASTM D-1238 (2.16 kg weight at 230°C.).

Molecular weight (weight-average molecular weight, M_(w), number-averagemolecular weight, M_(n), and molecular weight distribution, M_(w)/M_(n)or MWD) were determined using a High Temperature Size ExclusionChromatograph (either from Waters Corporation or Polymer Laboratories),equipped with a differential refractive index detector (DRI), an onlinelight scattering (LS) detector, and a viscometer.

Three Polymer Laboratories PLgel 10 mm Mixed-B columns were used. Thenominal flow rate was 0.5 cm³/min, and the nominal injection volume was300 μL. The various transfer lines, columns and differentialrefractometer (the DRI detector) were contained in an oven maintained at145° C. Polysytrene was used to calibrate the instrument.

Solvent for the SEC experiment is prepared by dissolving 6 g ofbutylated hydroxy toluene as an antioxidant in 4 L of Aldrich reagentgrade 1,2,4 trichlorobenzene (TCB). The TCB mixture is then filteredthrough a 0.7 μm glass pre-filter and subsequently through a 0.1 μmTeflon filter. The TCB is then degassed with an online degasser beforeentering the SEC. Polymer solutions are prepared by placing the drypolymer in a glass container, adding the desired amount of TCB, thenheating the mixture at 160° C. with continuous agitation for about 2 hr.All quantities are measured gravimetrically. The TCB densities used toexpress the polymer concentration in mass/volume units are 1.463 g/mL atroom temperature and 1.324 g/mL at 135° C. The injection concentrationranges from 1.0 to 2.0 mg/mL, with lower concentrations being used forhigher molecular weight samples. Prior to running each sample, the DRIdetector and the injector are purged. Flow rate in the apparatus is thenincreased to 0.5 mL/min, and the DRI was allowed to stabilize for 8-9 hrbefore injecting the first sample. The LS laser is turned on 1 to 1.5 hrbefore running samples.

The concentration, c, at each point in the chromatogram is calculatedfrom the baseline-subtracted DRI signal, I_(DRI), using the followingequation:c=K _(DRI) I _(DRI)/(dn/dc)where K_(DRI) is a constant determined by calibrating the DRI, and dn/dcis the same as described below for the LS analysis. Units on parametersthroughout this description of the SEC method are such thatconcentration is expressed in g/cm³, molecular weight is expressed inkg/mol, and intrinsic viscosity is expressed in dL/g.

The light scattering detector used is a Wyatt Technology HighTemperature mini-DAWN. The polymer molecular weight, M, at each point inthe chromatogram is determined by analyzing the LS output using the Zimmmodel for static light scattering (M. B. Huglin, Light Scattering fromPolymer Solutions, Academic Press, 1971):[K _(o) c/ΔR(θ,c)]=[1/MP(θ)]+2A ₂ cwhere ΔR(θ) is the measured excess Rayleigh scattering intensity atscattering angle θ, c is the polymer concentration determined from theDRI analysis, A₂ is the second virial coefficient, P(θ) is the formfactor for a monodisperse random coil (described in the abovereference), and K_(o) is the optical constant for the system:

$K_{o} = \frac{4\;\pi^{2}{n^{2}\left( {{{dn}/d}\; c} \right)}^{2}}{\lambda^{4}N_{A}}$in which N_(A) is the Avogadro's number, and dn/dc is the refractiveindex increment for the system. The refractive index, n=1.500 for TCB at135° C. and λ=690 nm. In addition, A₂=0.0015 and dn/dc=0.104 forethylene polymers, whereas A₂=0.0006 and dn/dc=0.104 for propylenepolymers.

The molecular weight averages are usually defined by considering thediscontinuous nature of the distribution in which the macromoleculesexist in discrete fractions i containing N_(i) molecules of molecularweight M_(i). The weight-average molecular weight, M_(w), is defined asthe sum of the products of the molecular weight M_(i) of each fractionmultiplied by its weight fraction w_(i):M _(w) ≡Σw _(i) M _(i)=(ΣN _(i) M _(i) ² /ΣN _(i) M _(i))since the weight fraction w_(i) is defined as the weight of molecules ofmolecular weight M_(i) divided by the total weight of all the moleculespresent:w _(i) =N _(i) M _(i) /ΣN _(i) M _(i)

The number-average molecular weight, M_(n), is defined as the sum of theproducts of the molecular weight M_(i) of each fraction multiplied byits mole fraction x_(i):M _(n) ≡Σx _(i) M _(i) =ΣN _(i) M _(i) /ΣN _(i)since the mole fraction x_(i) is defined as N_(i) divided by the totalnumber of molecules:x _(i) =N _(i) /ΣN _(i)

In the SEC, a high temperature Viscotek Corporation viscometer is used,which has four capillaries arranged in a Wheatstone Bridge configurationwith two pressure transducers. One transducer measures the totalpressure drop across the detector, and the other, positioned between thetwo sides of the bridge, measures a differential pressure. The specificviscosity, η_(s), for the solution flowing through the viscometer iscalculated from their outputs. The intrinsic viscosity, [η], at eachpoint in the chromatogram is calculated from the following equation:η_(s) =c[η]+0.3(c[η])²where c was determined from the DRI output.

The branching index (g′, also referred to as g′(vis)) is calculatedusing the output of the SEC-DRI-LS-VIS method as follows. The averageintrinsic viscosity, [η]_(avg), of the sample is calculated by:

$\lbrack\eta\rbrack_{avg} = \frac{\sum{c_{i}\lbrack\eta\rbrack}_{i}}{\sum c_{i}}$where the summations are over the chromatographic slices, i, between theintegration limits.

The branching index g′ is defined as:

$g^{\prime} = \frac{\lbrack\eta\rbrack_{avg}}{{kM}_{v}^{\alpha}}$where k=0.000579 and α=0.695 for ethylene polymers; k=0.0002288 andα=0.705 for propylene polymers; and k=0.00018 and α=0.7 for butenepolymers.

G′ is measured at the Mw of the polymer using the intrinsic viscosity ofisotactic polypropylene as the baseline. For use herein, the g′ index isdefined as:

$g^{\prime} = \frac{\eta_{b}}{\eta_{l}}$where ηb is the intrinsic viscosity of the polymer and ηl is theintrinsic viscosity of a linear polymer of the same viscosity-averagedmolecular weight (Mv) as the polymer. ηl=KMvα, K and α are measuredvalues for linear polymers and should be obtained on the same instrumentas the one used for the g′ index measurement.

The comonomer content and sequence distribution of the polymers can bemeasured using ¹³C nuclear magnetic resonance (NMR) by methods wellknown to those skilled in the art. Comonomer content of discretemolecular weight ranges can be measured using methods well known tothose skilled in the art, including Fourier Transform InfraredSpectroscopy (FTIR) in conjunction with samples by GPC, as described inWheeler and Willis, 47 APPLIED SPECTROSCOPY 1128-1130 (1993). For apropylene ethylene copolymer containing greater than 75 wt % propylene,the comonomer content (ethylene content) of such a polymer can bemeasured as follows: A thin homogeneous film is pressed at a temperatureof 150° C. or greater, and mounted on a Perkin Elmer PE 1760 infraredspectrophotometer. A full spectrum of the sample from 600 cm⁻¹ to 4000cm⁻¹ is recorded and the monomer wt % of ethylene can be calculatedaccording to the following equation: Ethylene wt%=82.585−111.987X+30.045X², where X is the ratio of the peak height at1155 cm⁻¹ and peak height at either 722 cm⁻¹ or 732 cm⁻¹, whichever ishigher. For propylene ethylene copolymers having 75 wt % or lesspropylene content, the comonomer (ethylene) content can be measuredusing the procedure described in Wheeler and Willis.

EXAMPLES

The thermoplastic olefin compounds of embodiments of the invention wereformulated in 16 mm Thermo Prism twin screw extruder. Compounding in thetwin screw extruder was accomplished using an intense mixing screwelement. The batch size was 1000 gm. The temperature profile in thevarious extruder zones was ramped progressively from 170° C. to 210° C.The compounds discharged from the extruder were pelletized.

Pellet Stability

Pellet stability of the samples was evaluated using small amplitudeoscillatory shear (SAOS). 2 gram samples of polymer were tested over aperiod of 1 hr. SAOS was conducted at 50° C., 40° C., and 30° C. Strainwas held constant at 0.5% in the linear viscoelastic region and thefrequency was varied from 100 to 0.1 rad/s. G′ and G″ values of thepolymer were measured and plotted versus frequency. The frequency atwhich the G′ and G″ value intersected were recorded as “crossoverfrequency.” The lower the crossover frequency, the better the pelletstability of the polymer. For polymers with superior pellet stability,very low or no (undetectable) crossover frequency may be observed.

Preparation of the Ethylene-Propylene Copolymer Blend.

All of the blends are made in solution or by melt blending in internalmixers or extruders. In all cases where multiple blending procedures aredescribed, each blend may be carried out in solution or in the melt.

All of the inventive blend composition polymers are physical blends ofan amorphous ethylene-propylene copolymer (EP), semi-crystalline EP, anda propylene-based elastomer (PBE). The ethylene-propylene copolymerblend may be made either as three individual components, namelyamorphous ethylene-propylene copolymer EP, semi-crystalline EP, and apropylene-based elastomer (PBE) which are blended together or as a blendof amorphous ethylene-propylene copolymer EP, semi-crystalline EP, whichis subsequently blended with the PBE. In a refinement of the blendingprocedure, the amorphous ethylene-propylene copolymer EP,semi-crystalline EP may be made in sequential or parallel polymerizationprocesses, blended during polymerization and recovered as a blend.Notwithstanding the sequence or the procedure of blending, the amorphousethylene-propylene copolymer EP and the semi-crystalline EP are eachmade in solution polymerization with 1,1′-bis(4-triethylsilylphenyl)methylene-(cyclopentadienyl)(3,8-di-tertiary-butyl-1-fluroenyl)hafniumdimethyl catalyst anddimethylaninliniumtetrakis(pentafluorophenyl)borate activator while thepropylene-based elastomer PBE is made dimethylsilylbis(indenyl)hafniumdimethyl catalyst anddimethylaniliniumtetrakis(heptafluoronaphthyl)borate activator.

All co-polymerizations for amorphous ethylene-propylene copolymer EP,semi-crystalline EP, and PBE were carried out in single-phaseliquid-filled, stirred tank reactors with continuous flow of feeds tothe system and continuous withdrawal of products under steady stateconditions. All polymerizations were done in a solvent comprisingpredominantly C₆ alkanes, referred to generally as hexane solvent, usingsoluble metallocene catalysts and discrete, non-coordinating borateanion as described above as co-catalysts. Hydrogen was added, ifnecessary, to control molecular weight. The hexane solvent was purifiedover beds of 3 A mole sieves and basic alumina. Reactor temperature wascontrolled adiabatically by controlled chilling of the feeds and usingthe heat of polymerization to heat the reactor. The reactors weremaintained at a pressure in excess of the vapor pressure of the reactantmixture to keep the reactants in the liquid phase. In this manner thereactors were operated liquid full in a homogeneous single phase.Ethylene and propylene feeds were mixed with a pre-chilled hexanesolvent stream. A hexane solution of a tri-n-octyl aluminum scavengerwas added to the combined solvent and monomer stream just before itentered the reactor to further reduce the concentration of any catalystpoisons. A mixture of the catalyst components in solvent was pumpedseparately to the reactor and entered through a separate port. Thereaction mixture was stirred aggressively to provide thorough mixingover a broad range of solution viscosities. Flow rates were set tomaintain an average residence time in the reactor of about 10 minutes.On exiting the reactor, the copolymer mixture from each reactor wascombined and subjected to quenching, a series of concentration steps,heat and vacuum stripping and pelletization, the general conditions ofwhich are described in International Patent Publication WO 99/45041,incorporated herein by reference in its entirety.

All polymer compositions in were synthesized in one continuous stirredtank reactors. The polymerization was performed in solution, usinghexane as a solvent. In the reactor, polymerization was performed at atemperature of 110° C. to 115° C., an overall pressure of 20 bar andethylene and propylene feed rates of 1.3 kg/hr and 2 kg/hr respectively.As catalyst, N,N-dimethylanilinium tetrakis(pentafluorophenyl)boron wasused to activatedi(p-triethylsilylphenyl)methenyl[(cyclopentadienyl)(2,7-di-tert-butylfuorenyl)]hafnium dimethyl. In the process, hydrogen addition and temperaturecontrol were used to achieve the desired melt flow rate. The catalyst,activated externally to the reactor, was added as needed in amountseffective to maintain the target polymerization temperature. Thecopolymer solution emerging from the reactor was stopped from furtherpolymerization by addition of water and then devolatilized usingconventionally known devolatilization methods such as flashing or liquidphase separation, first by removing the bulk of the hexane to provide aconcentrated solution, and then by stripping the remainder of thesolvent in anhydrous conditions using a devolatilizer or a twin screwdevolatilizing extruder so as to end up with a molten polymercomposition containing less than 0.5 wt % of solvent and othervolatiles. The molten polymer was cooled until solid.

The amorphous EP from the first polymerization and the semi-crystallineEP from the second polymerization were physically blended using anextruder. The batch size for twin screw compounding was 30 kg.Compounding in the ZSK extruder was accomplished by tumble-blending thetwo components (listed in Table 1) in a V-cone blender and introducingthe blend into the extruder hopper. The melt temperature was maintainedat 230° C.

An ethylene-propylene copolymers (EPR) was prepared by blendingamorphous ethylene-propylene copolymers with semi-crystallineethylene-propylene copolymers.

The propylene-based elastomer used throughout the examples is Vistamaxx™6102 performance polymer, commercially available from ExxonMobilChemical Company. Vistamaxx™ 6102 is a propylene-ethylene copolymerhaving a density of 0.862 g/cm³, melt index (at 190° C., 2.16 kg) of 1.4g/10 min, MFR of 3 g/10 min, and ethylene content of 16 wt %.

An ethylene-propylene copolymer (EPR) was prepared by blending amorphousethylene-propylene copolymers with semi-crystalline ethylene-propylenecopolymers.

TABLE 1 ETHYLENE-PROPYLENE COPOLYMERS Copolymer MFR C₂ C₃ Component(g/10 min) (wt %) (wt %) Amorphous Ethylene- 0.5 49.0 51.0 PropyleneCopolymer A1 Semi-crystalline 15.1 67.0 33.0 Ethylene-PropyleneCopolymer S1 Semi-crystalline 4.1 67.0 33.0 Ethylene-Propylene CopolymerS2 Semi-crystalline 0.8 68.0 32.0 Ethylene-Propylene Copolymer S3Semi-crystalline 14.0 73.7 26.3 Ethylene-Propylene Copolymer S4Semi-crystalline 11.0 74.6 25.4 Ethylene-Propylene Copolymer S5Semi-crystalline 1.6 74.0 26.0 Ethylene-Propylene Copolymer S6Semi-crystalline 5.5 76.5 23.5 Ethylene-Propylene Copolymer S7Semi-crystalline 2.3 79.0 21.0 Ethylene-Propylene Copolymer S8Example Compositions

Sixteen bimodal ethylene-propylene copolymers (EPRs) were prepared byblending 75 or 90 wt % of an amorphous ethylene-propylene copolymer ofTable 1 with 10 or 25 wt % of semi-crystalline ethylene-propylenecopolymer of Table 1. The pellet stability of the bimodal EPRs isreported in Table 2.

TABLE 2 BIIMODAL ETHYLENE-PROPYLENE COPOLYMERS Pellet Stability(Crossover of G″ and G′ Sample Copolymer Component at 30° C.) Sample 1EPR1 (90 wt % A1/10 wt % S1) 0.14 Sample 2 EPR 2 (90 wt % A1/10 wt % S2)0.09 Sample 3 EPR 3 (90 wt % A1/10 wt % S3) 0.06 Sample 4 EPR 4 (90 wt %A1/10 wt % S4) 0.03 Sample 5 EPR 5 (90 wt % A1/10 wt % S5) 0.01 Sample 6EPR 6 (90 wt % A1/10 wt % S6) 0.06 Sample 7 EPR 7 (90 wt % A1/10 wt %S7) 0.06 Sample 8 EPR 8 (90 wt % A1/10 wt % S8) 0.04 Sample 9 EPR 9 (75wt % A1/25 wt % S1) 0.04 Sample 10 EPR 10 (75 wt % A1/25 wt % S2) 0.03Sample 11 EPR 11 (75 wt % A1/25 wt % S3) 0.03 Sample 12 EPR 12 (75 wt %A1/25 wt % S4) None Sample 13 EPR 13 (75 wt % A1/25 wt % S5) None Sample14 EPR 14 (75 wt % A1/25 wt % S6) None Sample 15 EPR 15 (75 wt % A1/25wt % S7) None Sample 16 EPR 16 (75 wt % A1/25 wt % S8) None

Ethylene-propylene copolymers were prepared by blending 90 wt % EPRlisted in Table 2 with 10 wt % VMX 6102. It is appreciated that the useof the inventive copolymers, along with propylene homopolymers, and/orethylene plastomers, and/or fillers for thermoplastic olefincompositions displays improved performance as compared to conventionalethylene-alpha olefin polymers currently used for such compositions.

For all jurisdictions in which the doctrine of “incorporation byreference” applies, all of the test methods, patent publications,patents and reference articles are hereby incorporated by referenceeither in their entirety or for the relevant portion for which they arereferenced.

The invention claimed is:
 1. A polyolefin composition comprising: a.about 75 wt % to about 90 wt % based on the total weight of thecomposition of an amorphous ethylene-propylene copolymer having eitherno crystallinity or crystallinity derived from ethylene, having about 30wt % or more units derived from ethylene; b. about 5 wt % to about 25 wt% based on the total weight of the composition of a semi-crystallineethylene-propylene copolymer having substantial crystallinity derivedfrom ethylene and having about 70 wt % or more units derived fromethylene; and c. about 1 wt % to about 5 wt % based on the total weightof the composition of a propylene-based elastomer having within therange from 5 to 25 wt % ethylene derived units and having a meltingpoint temperature of less than 110° C. and a Mw/Mn within the range from2.0 to 4.0.
 2. The composition of claim 1, wherein composition is areactor blend of the amorphous ethylene-propylene copolymer, thesemi-crystalline ethylene-propylene copolymer, and the propylene-basedelastomer.
 3. The composition of claim 1, wherein the composition is aphysical blend of the amorphous ethylene-propylene copolymer, thesemi-crystalline ethylene-propylene copolymer, and the propylene-basedelastomer.
 4. The composition of claim 1, wherein the composition hasgreater about 70 wt % to about 80 wt % units derived from ethylene. 5.The composition of claim 1, wherein the composition is substantiallyfree of diene units.
 6. The composition of claim 1, wherein thepropylene-based elastomer has a melting point temperature within therange of from 80° C. to 110° C.
 7. The composition of claim 1, whereinthe composition has a total ethylene content within the range of 6 to 25wt %.
 8. The composition of claim 1, wherein the amorphousethylene-propylene copolymer has a melt flow rate of about 0.01 g/10 minto about 1 g/10 min.
 9. The composition of claim 1, wherein thesemi-crystalline ethylene-propylene copolymer has a melt flow rate ofabout 0.1 g/10 min to about 15 g/10 min.
 10. The composition of claim 1,wherein the amorphous ethylene-propylene copolymer has about 35 wt % toabout 55 wt % of units derived from ethylene.
 11. The composition ofclaim 1, wherein the semi-crystalline ethylene-propylene copolymer hasabout 70 wt % to about 80 wt % of units derived from ethylene.
 12. Anautomotive component made from the composition of claim
 1. 13. Apolyolefin composition comprising: a. about 80 wt % to about 90 wt %based on the total weight of the composition of an amorphousethylene-propylene copolymer having either no crystallinity orcrystallinity derived from ethylene, having from about 35 wt % to about55 wt % units derived from ethylene; b. about 5 wt % to about 15 wt %based on the total weight of the composition of a semi-crystallineethylene-propylene copolymer having substantial having substantialcrystallinity derived from ethylene, having from about 70 wt % to about80 wt % units derived from ethylene; and c. about 1.5 wt % to about 3.5wt % based on the total weight of the composition of a propylene-basedelastomer having within the range from 6 to 20 wt % ethylene derivedunits and having a melting point temperature of less than 110° C., amelt flow rate of about 0.1 g/10 min to about 3 g/10 min, and a Mw/Mnwithin the range from 2.0 to 4.0.
 14. The composition of claim 13,wherein the amorphous ethylene-propylene copolymer has a melt flow rateof about 0.01 g/10 min to about 1 g/10 min.
 15. The composition of claim13, wherein the semi-crystalline ethylene-propylene copolymer has a meltflow rate of about 0.1 g/10 min to about 15 g/10 min.
 16. An automotivecomponent made from the composition of claim 13.